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Re: Vacuum Pump and Whatnot...



Hi Michael,

Comments below.

> Original Poster: "Michael Novak" <Acmnovak-at-execpc-dot-com>
>My vacuum pump was taken from an old air conditioner and no
>longer can reach a very low pressure as it once could.  I am
>led to believe that it requires an oil change. However, I can't 
>get open the oil spout or whatever, it might have some kind of
>locking compound on the threads of the bolt which holds
> in the dipstick.  Would it be okay to put oil directly into the
>vacuum chamber through the input?   I thought I would consult
>the more experienced before making such a decision.

Usually, these kind of compressors are non serviceable and are
not really designed for vacuum work. However, they do indeed
work. Usually you can replenish the oil through the input, BUT
it depends on the internal design. I would spin up the pump,
unplug it and let it almost spin to a standstill. Then plunge the
input into a container with vacuum grade oil (motor oil gases
way too much). If your pump stalls, then you CAN`T fill it this
way. In fact you will damage it. However, if it spins down
normally, then you can replenish it this way.

One thing should be noted: These pumps depend on the oil
for cooling and lubrication. A fridge pump also depends on
the freon (etc), so it will get quite a bit hotter than normal.
This means keeping run times low. Also, they will spit out
minute quantities of oil, which makes replenishing necessary
and can make a big mess out of a vacuum experiment as the
oil vapors will contaminate the vacuum. Put the output (pressure)
side in a bucket of soapy water. The soap will bind the oily
vapor and help keep the experiment "clean".

Coiler greets from Germany,
Reinhard